Fable Brain

docs.claude.com

4 min read

docs.claude.com

docs.claude.com is Anthropic’s official Claude documentation site and this brain’s primary corroboration source; the three pages verified for this vault currently resolve under platform.claude.com/docs/en/ paths, all retrieved 2026-07-07.

What it is

The research pack holds no verified URLs for the Claude Code docs set or the prompt engineering set, and does not establish how the docs.claude.com and platform.claude.com hostnames relate (redirect, mirror, or migration). Verify a live URL before citing either doc set or asserting the hostname relationship.

How it works

  • What each verified page evidences:
    • Models overview: the current lineup and IDs (claude-fable-5, claude-mythos-5, claude-opus-4-8, claude-sonnet-5, claude-haiku-4-5-20251001), the pinned-snapshot ID policy, prices, context windows, and Mythos 5 availability.
    • Introducing Claude Fable 5 and Claude Mythos 5: shared specs (1M context, 128k output, January 2026 cutoff, Opus 4.7 tokenizer), adaptive thinking, Covered Model 30-day retention, availability surfaces, Glasswing access, and restored access after the export-control episode.
    • Refusals and fallback: the four refusal categories, the HTTP 200 refusal shape with stop_reason “refusal”, non-billing of pre-output refusals, and the three fallback paths to Opus 4.8.
  • How this brain cites the site, per Confidence Tag Policy:
    • A claim corroborated by a dated public Anthropic URL is EVIDENCE-BASED.
    • Every citation carries a retrieval date, formatted “(retrieved 2026-07-07)“.
    • An export-versus-docs conflict is CONTESTED until a newer official source resolves it.
    • Entries past refresh_due in the source ledger are stale and must be re-verified.
  • The claude.ai harness itself points the same direction: “Any time you would otherwise rely on memory for Anthropic product details, verify here instead” (System Prompt Export 2026-07, L3756-3758).

Best practice

  • Record a retrieval date on every docs citation; undated citations cannot pass Claim Verification Flow. EVIDENCE-BASED
  • Use the models overview page for lineup, ID, price, and context-window facts; it names every current pinned snapshot. EVIDENCE-BASED
  • Answer refusal and fallback questions from the refusals-and-fallback page, not the launch news post; the docs carry the operational detail. PRACTITIONER
  • Re-verify any docs claim past its refresh_due date in the source ledger before citing it as current. EVIDENCE-BASED
  • Check docs before training memory for any Anthropic product fact, mirroring the harness’s own product-self-knowledge rule. EVIDENCE-BASED

Pitfalls

  • Citing docs paths from memory; only the three URLs above are verified, and hostnames have shifted before.
  • Treating the launch announcement as spec-authoritative; docs pages carry the current values when the two drift.
  • Quoting Sonnet 5 introductory pricing (10 per MTok) as its list rate (15).
  • Expecting docs to describe consumer harness internals; the memory system, artifact runtime, and tool inventory live only in System Prompt Export 2026-07.
  • Forgetting that docs pages are living documents; a retrieval date is part of the claim, not decoration.

Sources

Next actions

  • Verify live URLs for the Claude Code docs set and the prompt engineering set, then close the gap callout.
  • Establish the docs.claude.com versus platform.claude.com hostname relationship with a dated check.
  • Add refresh_due entries for the three verified pages to the source ledger if missing.

Graph View

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